Lubricant compositions

ABSTRACT

4-ALKYLPHENYL-ALKYL-2-NAPHTHYLAMINES AND MIXTURES OF 4-ALKYLPHENYL-1-ALKYL-2-MAPHTHYLAMINES WITH 4-ALKYLPHENYL-2-NAPHTHYLAMINES ARE EFFECTIVE IN IMPROVING THE OXIDATION RESISTANCE, CLEANLINESS AND BEARING PERFORMANCE PROPERTIES OF LUBRICANT COMPOSITIONS.

United States Patent Oflice 3,660,290

Patented May 2, 1972 Exam les of the invent' 3,660,290 p we compounds include. LUBRICANT COMPOSITIONS t" Roland T. Schlo'bohm, Bethalto, Ill., assignor to Shell N O rr Oil Company, New York, NY. L i it No Drawing. Filed Sept. 22, 1969, Ser. No. 860,035

Int CL clom 1/34 i-octylphenyl-l-butyl-E-naphthy1amine U.S. Cl. 252-515 A 5 Claims 8 1-: J

N -C H @ioixffi a 1? ABSTRACT OF THE DISCLOSURE 10 h (m1 1 1 t l 2 uh 4-alkylphenyl-1-alkyl-2-naphthylamines and mixtures of 3 0c J thylamne 4-alkylphenyl-1-alky1-2-naphthylamines with 4-alkylphena 17 N yl-2-naphthylamines are effective in improving the oxida- W0 I I O 4439 tion resistance, cleanliness and bearing performance prop- H +-butylphenyl-l-octyl-E-naphthylamine and the like.

It has been further found that mixtures of the hereinerties of lubricant compositions.

This invention relates to a novel class of phenyl-2- befo re described alkylphenyl-alkylnaphthylammes with naphtllylamme denvatlves and to 1ubnant comPosltlons 20 phenyl-2-naphthylamines having alkyl substituents exclucontainlng such compounds. More particularly, it relates Sively on the phenyl ring also impart excellent perfonm to i i t i' 'i' w i m Whlch ance properties to ester base lubricant compositions; propfectrve 1n increasing the oxidation resistance, cleanliness erfies which in fact are Superior to those which would be and i' perfmmancapmgerfies of lubric?ting F expected from the use of these compounds individually. Lflbncants emploYed hlgh sPeed turbme g 5 Alkylphenyl-Z-naphthylamines which are suitable for partfcularly modem 2 alrFraft engme?! must be reslstant use in conjunction with the additives of the invention are to tempefratfre oxldatlve Search for those having one or more alkyl substituents on the phenyl add tives wh ch impart the requisite properties to such ring Said alkyl groups may contain from 2 to 16 carbon lubricating 0115 has led to the development of numerous atoms, but Preferably having 4 to 12 carbon atoms and oxidation inhi it for eXample Phenothiazine, phenyl a tertiary alkyl structure. Alkylphenyl-2-naphthylamines l-naphthylamine, phenyl-2-naphthylami and Various having a single tertiary-butyl or tertiary-octyl group subphenylamines. Certain alkylated phenyl-Z-naphthylamines stituted in the 4 position of the phenyl ring have been have also been Proposed these alkylated compounds found to be particularly elfective when used in combinaing Characterized by having one or more alkyl Substitu' tion with the present additives. Examples of such coments introduced into the phenyl nucleus. With the conpounds include:

tinual development of more powerful jet engines, however, and a corresponding increase in operating temperatures, many of the prior art additives have proved to be I inadequate in providing the required oxidation stability H to lubricating oils. Therefore, there is a need in the art 40 for the development of additives which will increase a 4-butylphenyl-Z-naphthylamine cause the formation of deposits.

It has now been found that 4-alkylphenyl-1-alkyl-2- lubricants resistance to oxidative degradation and which will not form sludge, develop high acidity or viscosity, or

naphthylamines are efiective in improving the oxidation resistance, cleanliness and bearing performance properties 11 D y aph y mnine of lubricatin oils. The eifectiveness of these com unds g p0 and the like. Compositions wherein the ratio of the alkylis attributed in substantial part to the presence of an alkyl substituent on the naphthyl nucleus which was found 0 f 'i i z i i to t P Substl to have a remarkable eifect on the performance character- P any P t y ammes 1s 3 to 1 very istics of the resulting compound. satisfactory especially those wherein the ratio is from 355 iggggfigigggt 2 naphthylamnes the m The alkylphenyl-alkylnaphthylamines of the invention are generally prepared by reacting phenyl-2-naphthyl R1 amine with a 1- or 2-alkene having from 2 to 16, or more, carbon atoms at an elevated temperature in the presence of a Friedel-Crafts catalyst, e.g., aluminum chloride. The H reaction conditions largely govern the nature of the alkylated products formed. Conditions conducive to naphthyl wherein R and R are alkyl groups having from 2 to 80, ring substitution are described in Example 1. Employing preferably from 2 to 16, carbon atoms. Compounds these conditions it is possible to introduce alkyl substituwherein the R and R substituents have from 4 to 12 ents into the naphthyl nucleus thus forming the unique carbon atoms and have a tertiary alkyl structure are compounds of the present invention. especially advantageous for use in the present composi- Lubricant base stocks suitable for the practice of the tions, particularly those wherein R and R are tertiarypresent invention include esters of alcohols having 1 to butyl or tertiary-octyl groups. 20, especially 4 to 12 carbon atoms andaliphatic car- The alkylphenyl-alkylnaphthylamines of the invention boxylic acids having from 3 to 20, especially 4 to 12 carcan be employed in lubricant compositions either singubon atoms. The ester base may comprise a simple ester larly, in mixtures, or in combination with alkylphenyl-2- (reaction product of a monohydroxyalcohol and a mononaphthylamines which have alkyl substituents exclusively carboxylic acid), a polyester (reaction productof an alon the phenyl nucleus. cohol and an acid, one of which has more than one functional group), or a complex ester (reaction product of a polyfunctional acid with more than one alcohol, or of a polyfunctional alcohol with more than one acid). Also, excellent synthetic lubricant may be formulated from mixtures of esters, such as major proportions of complex esters and minor amounts of diesters.

Examples of suitable ester base oils are ethyl palmitate, ethyl laurate, butyl stearate, di(2-ethylhexyl)sebacate, di (2-ethylhexyl)azelate, ethylene glycol diluarate, di-(Z-ethylhexyl)phthalate, di-(3-methylbutyl) adipate, di-(Z-ethylpropyl)azelate, diisopropyloxylate, dicyclohexyl sebacate, glycerol tri-n-heptanoate, di(undecyl)azelate, and tetraethylene glycol di-(2-ethy1 hexanoate), and mixtures thereof. An especially preferred mixture of esters consists of about 50 80% bis(2,2,4 trimethylpentyl)azelate and 20 to 50% 1,1,1'trimethyl propane triheptanoate.

Especially preferred esters for use as base stocks in the present invention are esters of monocarboxylic acids having 3 to 12 carbons and polyalcohols such as pentaerythritol, dipentaerythritol, trimethylolpropane and mixtures thereof. Examples of these esters are pentaerythrityl tetrabutyrate, pentaerythrityl tetravalerate, pentaerythrityl tetracaproate, pentaerythrityl dibutyratedicaproate, pentaerythrityl butyratecaproate divalerate, pentaerythrityl butyrate trivaler-ate, .pentaerythrityl butyrate tricaproate, pentaerythrityl tributyratecaproate, mixed C -C saturated fatty acid esters of pentaerythritol, dipentaerythrityl hexavalerate, dipentaerythrityl hexacaproate, dipentaerythrityl hexaheptoate, dipentaerythirtyl hexacaprylate, dipentaerythrityl tributyratetricaproate, dipentaerythrityl trivalerate tripelargonate, dipentaerythrityl mixed hexaesters of -0 fatty acids and trimethylyl-propane heptanoate. Mixtures of pentaerythrityl and dipentaerythrityl esters of C -C acids are particularly advantageous base oils, and are commercially available from Hercules, Inc.

In addition to the aforementioned synthetic oils, the additives of this invention may also be incorporated in mineral lubricating oils. The mineral lubricating oil can be obtained from parafiinic, naphthenic, asphaltic or mixed base crudes and/or mixtures thereof, for example neutral oils having viscosities of from 100 to 6500 SSU at 100 F.

The alkylpienyl-alkylnaphthylamines of the invention can be incorporated into lubricant compositions in amounts of from 0.01 to 10% by weight of the total composition. Concentrations of 0.5 to 5.0% by weight are generally sufiicient to impart the desired properties to lubricating oils. These concentration ranges are also ap plicable to mixtures of alkylphenyl-alkylnaphthylamines with alkylphenyl-naphthylamines as hereinbefore described. A preferred embodiment of the invention therefore is an ester base lubricating composition containing a total of from 0.01 to 10% by weight of a mixture of one or more 4-a1kylphenyl-1-alkyl-2-naphthylamines with one or more 4-alkylphenyl-Z-naphthylamines, the ratio of the former compounds to the latter being from 1:2 to 10:1.

Other additives recognized in the art to perform a particular function or functions can also be incorporated into the present compositions. These include viscosity improvers, e.g., methacrylate polymers and copolymers, additional antioxidants, corrosion inhibitors, antifoam agents, detergents and the like.

The invention will be further described by means of the following examples which demonstrate the manner of preparation and effectiveness of the inventive compounds and compositions. It should be understood, however, that these examples are given for illustrative purposes only and that the invention in its broader aspects is not limited thereto.

EXAMPLE I 5.36 g. (0.04 mole) of aluminum trichloride was added to 87.6 g. (0.4 mole) of phenyl-2-naphthylamine and heated to 120 C. While stirring and under a nitrogen atmosphere, 89.6 g. (0.8 mole) of diisobutylene was added dropwise to the reaction mixture over a period of one hour. After the addition of the diisobutylene, the reaction mixture was heated to 148 C. over a three hour period and the temperature maintained there for an additional two hours. The reaction mixture was then allowed to cool, mixed with two volumes of benzene, poured over ice and water, Washed with a 10% aqueous NaOH solu* tion and with distilled water until neutral, after which the benzene layer was dried over CaSO After filtering and removal of the benzene by distillation, the crude product (146 g.) was vacuum distilled over the range of 210/ 50 to 260 C./45/L, yielding 139 g. of product. 4-tertoctylphenyl-l-tert-octyl 2 naphthylamine was isolated by means of gas chromatographic preparative techniques and was identified by infra-red spectroscopy, nuclear magnetic resonance (NMR) and elemental analysis. This compound constituted 54.99% of the reaction product.

Gas chromatographic analysis also demonstrated the presence of a mixture of two other naphthyl-substituted henyI-Z-naphthylarnines constituting 15.79% of the reaction product. This mixture was separated from distilled product and identified by infra-red spectroscopy and nuclear magnetic resonance as being 4-tert-octylphenyl-ltert-butyl-2-naphthylamine and 4-tert-butylphenyl-l-tertoctyl-Z-naphthylamine.

EXAMPLE II TABLE I Additive, percent weight 4-tertoetyl- Phenylphenyl- 2-naph- Z-naph- Ease thyl thyl- Addi- Addi 01]. amine amine tive A tivo B 1 Equal molar concentrations equivalent to 1.0% w. phenyl-Z-naphthyl 2.1111116 in base oil.

Additives Additive 4-tert-octylphenyl-l-tert-octyl-Z-naphthylamine Additive B: Mixture of 4-tert-octylphenyl-1-tert-octyl-2- naphthylamine, 4 tert-butylphenyl-l-tert-octy1-2-naphthylamine and 4-tert-octylphenyl-1-tert-butyl-2-naphthylamine with 4 tert-octylphenyl-Z-naphthylamine, Ratio of alkylphenyl-alkylnaphthylamines to 4-tertoctylpheny1-2-naphthylamine is approximately 3 to 1.

Base Oils Base Oil W: Mixed C acid esters of pentaerythritol and dipentaerythritol containing 0.17% w. of phosphorus extreme pressure agents, 0.1% w. of triazole corrosion inhibitors, 0.25% w. of a copolymeric dispersant, 1.5% W. of an amine antioxidant, 0.02% of a. dibasic acid corrosion inhibitor and 10 ppm. silicone fiuid antifoamant.

Base Oil X: Base Oil W minus the copolymeric dispersant plus 2.0% w. additional phosphorus extreme pressure agent.

Base Oil Y: Base Oil X minus the dibasic acid corrosion inhibitor and 1.0% of phosphorus extreme pressure agent plus 0.5% w. of a triazine oxidation inhibitor and an additional 0.5 of the amine antioxidant.

Base Oil Z: Mixed C acid esters of pentaerythritol and dipentaerythritol containing 0.2% W. phosphorus extreme pressure agent and 0.5 w. of a triazole corrosion inhibitor.

EXAMPLE III To demonstrate the advantages of the present compositions in respect to oxidation stability and high temperature bearing performance, Compositions IV, V and VI, all prepared from Base Oil X, were subjected to a Bearing Rig Test under the very severe Type 2% conditions. The results of these tests are shown in Table II.

The Bearing Rig Test is described in Military Specification MIL-L-23699.

From the above data it is evident that Compositions V and VI of the invention have outstanding properties in respect to overall cleanliness and viscosity change as compared to Composition IV whech contains an equal molar concentration of a phenyl-Z-naphthylamine having no alkyl substituents on the naphthyl ring. It is indeed surprising that the addition of an alkyl substituent on the naphthyl nucleus (Additive A) would bring about such a significant improvement in the eifectiveness of the inventive compounds. Moreover, it is equally remarkable that Composition VI, which contains a combination of the additives of the invention with the additive employed in Composition IV, has an overall demerit rating superior to that of either Compositions IV or V containing the additives individually, i.e., a total demerit rating of 28.2 as compared to 69 and 38.6 respectively.

EXAMPLE IV A further indication of the stability of the compositions of the invention was obtained by subjecting samples of Compositions VII and VIII to the Alcor High Temperature Deposition Test. Basically this test involves circulation of aerated oil over a heated deposition tube. The temperature of the tube is controlled at 525 F. on the inlet side and reaches 650 to 700 F. at the outlet end of the tube. The temperature profile of the tube is measured at the start and shortly before the end of the test. These temperature profiles and the tube deposits per unit length are used to determine the performance of the oil. The critical temperature is that temperature at which deposits begin to significantly affect the heat transfer characteristics of the oil. A temperature of about 600 F. is considered to be very satisfactory. The overall deposit rating is obtained from a combination of the visual deposit rating of the tube, the tube deposit weight and the filter deposit weight. An overall rating of less than 50 is considered very good, a rating of below is considered exceptional. A detailed description of this test is given in Proceedings of the USAF-Southwest Research Institute Turbine Lubrication Conference, September 13-15, 1966, Southwest Research Institute, San Antonio, Texas, page 152. Test results are shown in Table III.

The foregoing results indicate that Composition VIII of the invention, has a significantly less tendency to form deposits than Composition V-II which is prepared from the same base oil as Composition VIII but contains an alkylated phenyl-Z-naphthylamine not in accordance with the invention.

EXAMPLE V In order to further evaluate the antioxidation and anticorrosion properties of the present compositions, a series of Corrosion and Oxidation Stability Tests were run in accordance with the procedures set forth in Military Specification MIL-b23699. In addition, Compositions IX, X, and XI were subjected to a Micro-Air Oxidation Test. In this test, air at the rate of 30 ml./min. was passed through a 20 g. sample of the test lubricant which was maintained at a temperature of 425 F. The results of the test are expressed as oxidation life of the lubricant, which is defined as the time required for the adsorption of 3 millimoles of oxygen per gram of oil sample. The results of the Micro-Air Oxidation Test and the Corrosion and Oxidation Stability Test are shown in Table IV.

TABLE IV [Corrosion and oxidation stability, 400 F., 72 hours] Composition- I II III Weigl {it change of specimens:

*It is evident from the Corrosion and Oxidation Test results, that Compositions II and III of the invention have surprisingly less tendency to form sludge than Composition I which contains a molar equivalent of an additive not in accordance with the invention. In the Micro-Air Oxidation Test, Composition XI of the invention had a significantly longer oxidation life than either Composition IX containing phenyl-2-naphthylamine, or Composition X containing an equivalent amount of a phenyl-Z-naphthylamine having an alkyl substituent on the phenyl ring alone.

I claim as my invention:

1. A lubricant composition consisting essentially of a major amount of lubricating oil and an oxidation-inhibiting amount of a mixture of at least one 4-alkylphenyl-1- alkyl-2-naphthylamine with at least one 4-alkylphenyl-2- naphthylamine wherein said alkyl substituents have up to 16 carbon atoms and are tertiary alkyl substituents and the ratio of said alkylphenylalkylnaphthylamines to the alkylphenyl-naphthylamines is from 1:2 to 10:1.

2. The composition of claim 1 wherein the oxidation inhibiting mixture is present in the amount of from 0.01 to 10% by weight.

3. The composition of claim 1 wherein the lubricating oil is an ester of a monocarboxylic acid having 3 to 12 carbon atoms and a polyhydroxy compound selected from the group consisting of pentaerythritol, dipentaerythritol, trimethylolpropane and mixtures thereof.

4. The composition of claim 3 wherein all of the alkyl substituents are selected from the group consisting of tertiary-butyl and tertiary-octyl.

5. The composition of claim 4 wherein the ester lubricating oil is a mixed C acid ester of pentaerythritol and dipentaerythritol and the oxidation-inhibiting mixture is a mixture of 4-alkylphenyl-l-alkyl-Z-naphthylamines with 4-tert-octylphenyl-Z-napthylamine.

8 References Cited UNITED STATES PATENTS 2,009,480 7/1935 Craig 252-50 3,052,632 9/1962 Loefiier 25251.5 A

3,121,691 2/ 1964 Eickemeyer 252-50 X 3,505,225 4/ 1970 Wheeler 25250 X 3,509,214 4/1970 Braid et a1. 252-50 X FOREIGN PATENTS 1,429,495 1/1966 France 252-50 DANIEL E. WYMAN, Primary Examiner W. J. SHINE, Assistant Examiner US. Cl. X.R. 252-50, 390, 401 

